The present invention relates generally to semiconductor fabrication and more specifically to reworking of semiconductor wafers by removing polysilicon films.
Many times wafers must be scrapped if they suffer from thickness abnormally or particle problems after polysilicon deposition.
U.S. Pat. No. 5,928,969 to Li et al. describes a method for controlled selective polysilicon etching employing an NH4OH plus NH4F polysilicon etch and a hemispherical grain (HSG) polysilicon process.
U.S. Pat. No. 6,100,203 to Kil et al. describes a polysilicon etch and subsequent aqueous cleaning composition cleaner methods.
U.S. Pat. No. 5,431,777 to Austin et al. describes methods and compositions for the selective etching of silicon.
U.S. Pat. No. 5,296,093 to Szwejkowdki et al. describes a process for removal of residues remaining after etching a polysilicon layer.
U.S. Pat. No. 5,030,590 to Amini et al. describes a process for etching a polysilicon layer in the formation of an integrated circuit structure.
U.S. Pat. No. 4,113,551 to Bassous et al. describes a method for polycrystalline silicon etching with tetramethylammonium hydroxide.
U.S. Pat. No. 5,963,804 to Figura et al. describes a method of making a doped silicon structure with an impression image on opposing roughened surfaces.
U.S. Pat. No. 5,976,767 to Li describes a process for selectively removing silicon containing material using an ammonium hydroxide etch.
Accordingly, it is an object of an embodiment of the present invention to provide an improved method of selectively removing polysilicon.
Other objects will appear hereinafter.
It has now been discovered that the above and other objects of the present invention may be accomplished in the following manner. Specifically, a structure having a non-silicon layer formed thereover is provided. A first polysilicon layer is formed upon the non-silicon layer. The first polysilicon layer is removed from over the non-silicon layer to expose the non-silicon layer using a NH4OH:DIW dip solution process having a NH4OH:DIW ratio of from about 1:2 to 1:8. Whereby the non-silicon layer is substantially unaffected by the NH4OH:DIW dip solution process.